Automatic reclosing-circuit-breaker system



A ril p 1927 B. w. JONES AUTOMATIC RBI CLOSING CIRCUIT BREAKER SYSTEMFiled Dec. 20 9 1 amin wmlbvwes u MMZQW;

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Patented Apr. 26, 1927.

1 UNITED STATES PATENT OFFICE.

BENJAMIN W. JONES, OF SCI IEKEGTLDY, NEW YORK, ASSIGNOR TO GENERALELECTRIC 001mm. A CORPORATION OF NEW YORK.

AUTOMATIC REOLOSING-CIRCUIT-BREAKER SYSTEM.

Application fle ineoember S0, 1921. Serial No. 523,768.

My invention relates to automatic reclos; ing circuit breaker systemsand particularly to such systems in which a circuit breaker is relay 8.The relay 8 in the particular embodiment illustrated comprises a coil 9ar- 0 arranged to connect automatically a source of current to a loadcircuit as soon as the load conditions are such that the circuit breakercan be closed without overloading the source.

It is well known that in such systems, in which the load circuit issupplied With current at a plurality of points, there are'two differentconditions under which the automatic reclosing circuit breaker, whichcontrols the connection betweenv a source of current and the loadcircuit, must -'function properly to connect the source to the commonload circuit. ()ne of these conditions is when circuit breakers in allotthe other feeders supplying current to the common load circuit areopened and the other condition is when one or more of the circuitbreakers in the other feeders are closed, and one object of my inventionis to .pro-

vide a'new and improved automatic re-' closing circuit breaker s stemwhich willfunction ditions.

My invention will be better understood from the following descriptiontaken in con nection with the accompanying drawing, and its scope willbe pointed out in the appended claims. Referring to the accompanyingdrawing, Fig. 1' is a diagram showing an automatic reclosing circuitbreaker ystem embodying my invention; and. Fig. is a modification of thearrangement shown in Fig.1.

' Referring to Fig.1, 1 represents a source of current, such as a directcurrent generator, which is arranged to be connected to-a load properlyunder t iese difierent concircuit 2 by means ofan automatic reclosingcircuit breaker '3. \Vhile the automaticreclosing circuit breaker 3 isshown as being of the ccntactor type and is closed and held in itsclosed position by the energization of the closing coil 4. it is evidentthat my'inrention is not limited to this particular type of circuitbreaker and that any other well known type may be used. The load circuit2 is also shown as being arranged to be supplied with current fromanother source 1' which is arranged to be connected to the loiulcircui'tby means of a circuit breaker 3' which may be closed either manually orautomatically.

The closing coil el'is connected to any suitable source of current, suchas the generator 1, bymeans of the contacts 6 of a control ranged tocontrol the core 10 and connected in series with the load circuit, and ashunt coil 11 arranged to control the core 12 and connected in parallelwith an impedance 13 which is connected in series with the generator 1and the load circuit 2 when the circuit breaker 3 is opened. Theimpedance 13 is connected to the main terminals of the circuit breaker 3so that it is short 'circuited when the circuit "breaker is closed andtherefore the coil 11 is also short circuited when the circuit breakeris closed and the core 12 is in its unattracted position, in whichposition it closes the contacts 6. .The core 10 when attracted by theseries overload coil 9 engages the core 12 and moves it into its.attracted position thereby, opening the contacts 6 so that the closingcoil 4 is deenergized and the circuit breaker 3 is opened. Theopening ofthe circuit breaker inserts the 90 impedance 18 in series with the loadcircuit and so long as there is an-overload connected to the loadcircuit, the voltage drop across this impedance is suflicient to causethe coil 11 to maintain the'core 12 in its attracted position.Consequently the contacts 6 are not opened when the core 10 dropsdowndue to the decrease in the load current produced by the insertionof-the impedance 13 into the loadcircuit. The contacts 6 remain openuntil the condition of the load circuit is such that the circuit breaker3 can be closed with.- out'overloading the source 1. The relay 8 may bearranged in any suitable manner to dela I the closing. ofthe contacts 6after they ave been opened. In

the particular embodiment ofmy invention shown in the drawing, thisresult is obtained by means of a dash-pot'15' connected to the core 10.Furthermore the relay 8 may be 9 constructed in any suitable manner suchas is disclosed in Carichofi Patent 1,091,630,

which is assigned to the same assignee as this application, whereby thecore 12 will always drop at substantially the same value of currentirrespective of the position of the core 12 within certain limits.

In order to change the setting of the coil 11, so that the core 12 dropsdown and closes the contacts 6 in response to a difierent voltage dropacross the impedance 13 when the load circuit 2 is supplied from someother source than when the load circuit is not supplied from some othersource, I provide the impedance 20 in series with the coil 11 and therelay 21 for short circuiting this impedance when some other main sourceis connected to the load circuit 2.

In order to make the relay 21 short circuit the impedance 20 when someother source is connected to the load circuit 2, I connect the coil 22of the relay 21 directly across the load circuit 2 and design the relayso that it will close its contacts 23 when the voltage across the loadcircuit is above a predetermined value. The winding 22 may, however. beconnected to the load circuit in any other suitable manner so that therelay will be controlled by the voltage across the load circuit due tosome other source being'connected thereto to change the setting of thecoil 11.

The operation of the embodiment of my invention shown in Fig. 1 is asfollows: Under normal operating conditions the circuit breakers 3 and 3'are closed and the circuit of the closing coil 4 is completed throughthe contacts 6 of the control relay 8. Upon the occurrence of anoverload or short circuit on the load circuit 2, the overload coil 9attracts the core 10 so that the core 12 is pushed up into the coil 11and the contacts 6 are opened. The closing coil 4 becomes deenergizedand the circuit breaker 3 opens therebyinserting the impedance 13 inseries with the sourcel and the load circuit 2. The impedance 13 is sodesigned that if the load resistance is below a predetermined value. thevoltage drop across the impedance is sufiicient to cause the coil 11 tohold the core 12 in its attracted position. As soon as the circuitbreaker 3 opens, the current through the series coil 9 is not sufiicientto maintain the core 10 in, its attracted position. The core 10 dropsbut this movement is delayed by the dash-pot 15 so that contacts 6cannot be closed until aafter the opening of predetermined interval thebreaker.

If the short circuit or overload opens the circuit breaker 3', thevoltage across the load circuit 2 decreases to a very low value therebyindicating'that normal potential is not being impressed upon the loadcircuit at some other point. and the relay 22 opens its contacts 23thereby inserting the impedance 20 in series with the coil 11 so that averv small current is supplied to the load circuit "from the source 1.It is evident that when the impedance 20 is connected in series with thecoil 11, the core 12 will drop down and close the contacts 6 in responseto a higher voltage drop across the impedance 13 than when the impedance20 is short circuited.

Let it be assumed that the short circuit or overload has opened thecircuit breaker 3' so that the contacts 23 of the relay 22 are open.. Solong as the overload or short circuit remains connected to the loadcircuit, the drop across the impedance 13 is sufiicient to keep the core12 in its attracted position. As the load resistance increases thevoltage across the load circuit increases and the voltage drop acrossthe impedance 13, which is the difference between the voltages of thesource and the load circuit, decreases. lVhen the load resistancereaches a predetermined value, the voltage drop across the impedancebecomes sufficiently low to cause the core 12 to drop and close thecontacts 6 thereby completing the circuit of the closin coil .4 to closethe breaker.

Trot it nowbe assumed that the short circuit or overload on the loadcircuit does not open the circuit breaker 3'. The voltage across theload circuit 2 then remains high enough to maintain the relay 21 in itsattracted position so that the impedance 20 is short-circuited. The coil11 now mainiains the core 12 in its attracted position until the voltagedrop across the impedance 13 is equal to a predetermined diiicrcucebetween the voltages of the source 1 and the load .circuit 2. \Vhen thecore 12 drops down the contacts 6 are closed and the closing coil 4energized to reclose the breaker 3.

From the above description it is evident that with this arrangement thecircuit breaker 3 closes in response to a voltage drop across'theimpedance 13 corresponding to a predetermined difference in the voltagesacross the source and the load circuit when the load circuit is suppliedwith current-from some other main source and closes in response to avoltage drop corresponding to a predetermined load resistance when theload circuitis not supplied from some other main source.

The modification of my invention shown in Fig. 2, is similar tothe'emhodimcut shown in Fig. 1 except that the impedance 20 is replacedby an electron discharge tube 3) which is connected so that the currentthrough it is varied in accordance with the load resistance and the coil22 of the relay 21 is connected in parallel with the impedance 13instead of directly across the load circuit. In this particularembodiment of my invention the electron discharge tube 30 comprises acathode 31 of filamentary form, an anode 32 and a grid 33 interposedbetween thecathode and anode. The anode and cathode are connected inseries with the coil 11 of the control relay 8, the anode 32 beingconnected so that the potcntial impressed thereon is positive relativeto the potential of the cathode 31. The circuit through the electrondischarge tube 30.-however, is normally short circuited bv the contacts23 of the relay 21, which in this modification are closed when the relaycoil 22 is deenergized. The grid 33 is connected to the load circuit sothat the potential thereon becomes more negative with respect to thecathode 31 as the load resistance increases. The heating circuit of thefilament 31 is arranged to be connected to any suitable source ofcurrent, such as the battery 35 by means of the auxiliary contacts 36 ofthe circuitbreaker 3 when the circuit breaker is opened. The coil 37 ofa relay 38 is connected in series withthe filament 31. The relay 38controls contacts 39 in the circuit of the coil 22 so that it isdeencrgized when the heating circuit of the filament is open.

The operation of this modification of my invention is similar to theoperation of the embodiment shown in Fig.1.. Vhen an overload or shortcircuit occurs on the load circuit. 2, the overload coil 9 attracts thecore 10 which in turn mov s the core 12 upwardly into the coil 11 andopens the contacts '6. The closing coil 4: then becomes deenergized andcircuit breaker 3 opens. The opening of the circuit breaker closes thecontacts 36 thereby completing the heating circuit of the filament 31.Relay 38 then operates and connects the coil-22 across the terminals ofthe impedance 13. It the overload or short circuit does not open thecircuit breaker 3', the voltage across the load circuit remains highenough so that the voltage drop across the impedance 13, which is thedifference between the voltages across the source 1 and the load circuit2, is not suflicient to cause the relay 21 to open its contacts 23. Theelectron discharge tube 30 is then short circuited and the reclosing' ofthe circuit breaker 3 is controlled by the difference in the voltageacross the source and the load circuit in the same mariner as in Fig. 1.If, however, the circu t breaker 3' is opened by the overload or shorton- Qcuit the voltage across the load circuit drops to a low enough'value' so that. the voltage drop across the impedance 13'is sufficientto operate the relay 21. The current through the coil .11 now flows fromthe coil 11 through the tube Ell) to. the load side .of the impedance1%) instead of through the contact 23. So long as the load resistance isbelow a predetermined value the resist-' ance of the tube 30 is suchthat the current through the coil 11 is sutlicjent to hold the core 12in its attracted position. As the load resistance increases the-grid 33becomes a more negative with respect to the cathode 3 so that theresistance of the tube increases and the current through the tube and.coil 11 decreases. When the load resistance reaches a predeterminedvalue the current throughthe coil 11 becomes iusutticient to maintainthe core 12 in its attracted position. The core 12 then drops and closes.the contacts 6 thereby completing the circuit of the closing coil 4 toclose the breaker 3.

Since a very small change in the relative potentials of the grid andcathode of an electron discharge tube produce a very large change in theresistance of the tube, it is evident that a very small change in theload resistance produces a large change in'the resistanceof the tube 30.Consequently, with this arrangement the operation will be very sensitiveeven though the impedance 1.3 be made very great compared to the fullload resistance since by means of the electron discharge tube 30 therelay 8 is responsive to the very small change in volt-age drop acrossthe impedance produced by the load resistance increasing from itsoverload or short circuit value to its normal full load burn out or theheatingcircuit of the filament should be interrupted in any other way,the circuit breaker would be closed ir respective of the load resistanceWhenthe relay 21 opens its contacts 23 since the current throughitwould, under these conditions, drop to zero. In order to prevent thecircuit breaker from reclosing under these conditions,I provide thecoil'37 of the relay 38 in series with the heating circuit of thefilament so that if the filament circuit is open, the contacts 39 ofthe-relay 38, which controls the circuit of the coil 22, are also open.onsequently the contacts 23 of the relay 21 .remain closed and shortcircuit the tube 30 so that the circuit breaker 3 remains open until thevoltage drop across the impedance 13 drops below the predetermined"value at which the coil 11 is set to operate when the load circuit issupplied fromsomeother source.

\Vhile'I have shown and described several embodiments of my invention, I(lo not desire to be limited to the exact arrangecure by Letters Patentof the United States,-

1. In an automatic reclosing circuit breaker system, the combinationwith a supply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and said loadcircuit, and closing means for said circuitbreaker, of means controlled by the difference between the voltagesacross said two circuits when said. circuit breaker is open forcontrolling the said closing means, and mcunsarrangcd to be affected bya condition of said load circuit for determining the predeterminedvoltage difference at which said last mentioned ply circuit, a loadcircuit connected to said supply circuit, a circuit breaker adapted tocontrol the connection between said supply circuit and said loadcircuit, and clos- 111;; means for said circuit breaker, of meansarranged to be affected by the difference between the voltages acrosssaid two circuits when said circuit breaker is open for controlling thesaid closing means, and means responsive to a predetermined differencebetween the voltages across said two circuits for varying the setting ofsaid last-mentioned means so that said last mentioned means responds toeii'cct the operation of said closing means.

3. in an automatic reclosing circuit breaker system, the combinationwith a su ply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said sup--ply circuit and said load circuit, and closing means for said circuitbrcakcr, of a relay connected across the terminals oi said circuitbreaker when said breaker is open, and means controlled by a conditionof the load circuit for varying the impedance of the circuit. of saidrelay to vary the setting thereof.

4. In an automatic reclosing circuit breaker system, the combinationwith a supply circuit, a load circuit connected to'said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and said load circuit, and closlng means for saidcircuitbreaker, of means operative to effect the operation of said closin;: means when the difference between the voltages across saidcircuits is less than a predetermined value but greater than a secondpredetermined value and operative to effect the operation of saidclosing means when the difference between the voltages across saidcircuits is less than a third predetermined value which is less thansaid said second predetermined value.

5. 'In an automatic reclosing circuit breakor system, the combinationwith a supply circuit, a load circuit connected to. said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit. and' said' load circuit, and closing means "for said circuitbreaker. of means operative to gove'rn' the operation of said closinmeans in accordance with the difference between the' voltages acrosssaid circuits under one condition of the load circuit and operative togovern the operation of said closing means in accordance with the loadresistance under another condition of v the load circuit.

er system, the combination with a supply circuit, a load circuitconnected to said supply circuit, a circuit breaker adapted to controlthe connection between the said supply circuit and saidload circuit, animpedance arranged to be connected in series with said supply circuitand load circuit when said circuit breaker is open, andrclosing meansfor said circuit breaker, of a relay connected to said impedance andarranged to control the operation of said closing means and meanscontrolled by a' condition of the load circuit for varying the settingof said relay.

7 In an automatic reclosing circuit breaker system, the combination witha supply circuit, a load circuit connected to said supply circuit, acircuit breaker adapted to con trol the connection between said su plycircuit and said load circuit, an impedimce arauged to be connected inseries with said supply circuit and load circuit when said circuitbreaker is open, and closing means for said circuit breaker, of a relayconnected in parallel with said impedance and arranged to control theoperation of said. closing means, and means controlled by the voltage ofthe load circuit for varying the impedance of the circuit of said relay.

8. In an automatic reclosin'g circuit break- .er system, the combinationwith a supply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and said load circuit, an impedance arranged to be connected inseries with said supply circuit and load circuit when said circuitbreaker is open, and closing means for said circuitbreaker, of a relayconnected in parallel with said impedance and arranged to control theoperation of said closing means, 'means for varying the impedance of thecircuit of'said'relay in accordance with the load resistance, and meanscontrolled by acondition of the load circuit for rendering saidimpedance varying means ineffective.

9. In an automatic reclosing circuit breaker system, the combinationwitlra supply circuit, a. load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuitand said load circuit, an impedance arranged to be connected inseries with said supply circuit and load circuit when'said' circuitbreaker is open, and closing means for said circuit breaker, of a relayconnected in parallel. with said impedance and arranged to control theoperation of said closing means, means for varying the impedance of thecircuit of sail relay in apcordance with the load resistance, andmeanscontrolled by the voltage of the load circuit for short oircuitingsaid impedance varying means.

- 10. In an automatic reclosing circuit breakor system, the combinationwith a supply load circuit and operative to govern the operation of saidclosing means in accordance with the load resistance underanothercondition of the load circuit.

11, In an automatic reclosing circuit breaker system, the combinationwith a supply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and saidload circuit, an impedance arranged to be connected inseries with said supply circuit and load circuit when said circuitbreaker is open, and closing means for said circuit breaker, of a relayconnected in parallel withsaid impedance and arranged to control theoperation of said closing means, an electron discharge tube adapted tovary the impedance of thecircuit of said relay in accordance with theload resistance, and means controlled by a condition of the load circuitfor rendering said electron discharge tube inoperative to control theimpedance of said relay circuit,

12. In an automatic reclosing circuit breaker system, the combinationwith a supply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and said load circuit, an impedance arranged to be connected inseries with said supply circuit'and load circuit when said circuitbreaker is open, and closing means for said circuit breaker, of a relayconnected in parallel with said impedance and arranged to control theoperation of said closing means, an electron discharge tube having itscathode and anode connected in series with said relay and its gridconnected to said load circuit so that variations in the load resistancevaries the impedance of said relay circuit, and means controlled by thevoltage of said load circuit for rendering said electron discharge tubeinoperative to control the impedance of said relay circuit.

13. in an automatic reclosing circuit breaker system, the combinationwith a supply circuit, aloud circuit connected to said supply circuit, acircuit breaker adapted to control the connection between said supplycircuit and said load circuit, an impedance arranged to be connected inseries with said supply circuit and load circuit when said circuitbreaker is open, and closing means for said circuit breaker, of a relayconnected in parallel with said impedance and arranged Y to control theoperation of said closing means,'an electron discharge tube having itscathode and anode connected in series with said relay and its gridconnected to said load circuit so that variations in the load resistancevaries the impedance of said relay circuit, and a heating circuit forthe cathode of said tube arranged to be completed when said circuitbreaker is open.

i l. in an automatic reclosing circuit breaker system, the combinationwith a-supply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and said load circuit, an impedance arranged to be connected inseries with said supply circuit and load circuit when said circuitbreaker is-open, and closing means for said circuit breaker, of a relayconnected in parallel .with said impedance and arranged to control theoperation of said closing means, an electron discharge tube having itscathode and anode connected in series with said relay and its gridconnected to said load circuit so that variations in the load resistancevaries the resistance of said relaycircuit, and a second relay connectedin parallel with said impedance and arranged to complete a lowresistance circuit around the cathode and anode of said elec trondischarge tube when the voltage drop across said impedance is less thana pie determined value and to 0 en said low resistance' circuit whenthe-v0 tage drop across said impedanceis greater than said predeterminedvalue. r

15. In an automatic reclosing circuit breaker system, the combination:with a supply circu1t,a loadcircuit connected to said supply circuit, acircuit breaker adapted to control the connection between said supplycircuit and said load circuit, an impedance arranged tobe coimected inseri'eswith said supply circuit and load circuit when said I circuitbreaker is open, andclosing means for said circuit breaker, of a relayconnected in parallel with said impedance and arranged to control theoperation of said closing means, an electron discharge tube having itscathode and anode connected in series with said relay and its gridconnected to said load circuit so that variations in the load resistancevaries the impedance of said relay circuit, a second relay arranged toopen and close a low resistance circuit around said cathode and anode, acircuit for said second relay, contacts in said last mentioned circuit,a heatingcircuit for the cathode-of said electron discharge tube, and

means arranged to control said contacts so that said second relay isinoperative to open said low resistance circuit around said cathode andanode when said heating circuit is open.

16. In an automatic reclosing circuit breaker system, the combinationwith a sup ply circuit, a load circuit connected to said supply circuit,a circuit breaker adapted to control the connection between said supplycircuit and said load circuit, an impedance arranged to be connected inseries with said supply circuit and load circuit when said circuitbreaker is open, and closing means for said circuit breaker, of a relayconnected in parallel with said impedance and arranged to control theoperation of said closing means, an electron discharge tube having acathode and an anode connected in series with. said relay and a gridconnected to said load circuit so that variations in the load'resistancevaries the impedance of said relay circuit, a second relay connected inparallel with said first impedance and arranged to complete a lowresistance circuit around the cathode and anode when the difference in.the voltages across said circuits is less than a predetermined value andto open said low resistance circuit when the difference in the voltagesis greater than said predetermined value, contacts in the circuit ofsaid second relay, a heating circuit for the cathode of said electrondischarge tube, and

a third relay connected in said heating circuit and arranged to controlsaid contacts so that said second relay is inoperative to open said lowresistance circuit across said cathode and anode if said heating circuitis open,

17. In an automatic reclosing circuit breaker system, two electriccircuits, a circuit breaker for connecting said circuits to gether,electroresponsive means for controlling the closing of said circuitbreaker having a coil so connected when the circuit breaker is open andthat its energizution is controlled b the voltage across one of saidcircuits, an means operative in accordance with a predeterminedcondition of said one of said circuits when said circuit breaker is opento vary the setting of said electroresponsive means whereby saidelectroresponsive means operates to effect the closing of said circuitbreaker in response to one predotermmed condltion of sa1d one of saidcirwhen the circuit breaker is open that its energization is controlled'by the voltage across the load circuit, and means operative inaccordance with a predetermined condition oi said load circuit when thecircuit breaker is open to vary the setting of said reclosing relaywhereby said reclosing relay operates to efifect the closing of saidcircuit breaker in response to one predetermined electrical condition ofsaid load circuit under certain conditions and in response to anotherpredetermined electrical condition of said load circuit under otherconditions.

1.9. in an automatic reclosing circuit breaker system, a supply circuit,a, load circuit' arranged to be supplied with current at a plurality ofpoints, a circuit breaker for connecting said supply circuit to saidload. circuit, an impedance arran ed to be connected in series betweensaiu circuits when the circuit breaker is open, a reclosing relay forcontrolling the reclosing of the circuit breaker having a coil soconnected when the circuit breaker is open that its energization iscontrolled by the voltage across the load circuit, and means controlledby the voltage across the load circuit for controlling the connectionsof said reclosiug relay whereby said relay efiects the closing of saidcircuit breaker in response to a predetermined electrical condition ofthe load circuit when it is not supplied with current at substantiallynormal potential at some other point and in response to a difierentpredetermined electrical condition of the load circuit when it issupplied with current at substantially normal potential at some otherpoint,

In witness whereof, I ha've'hereunto set my hand this 19th day ofDecember, 1921.

BENJAMIN W. (TUNES.

(ill

